I'm sorry you're having trouble. Do you have version info available? I just tested it on Windows 7, Firefox 28 and it worked. I started building this in Firefox, though now I mostly use Chrome (IDK, Firefox has felt like a beast lately, and I get antsy with browsers).
Sometimes, not all of the javascript files load in the right order and an error occurs because of a dependency. I'm fixing it right now, but maybe reloading the page will help with your issue.
I'm sorry you're having trouble. Do you have version info available? I just tested it on Windows 7, Firefox 28 and it worked. I started building this in Firefox, though now I mostly use Chrome (IDK, Firefox has felt like a beast lately, and I get antsy with browsers).
Sometimes, not all of the javascript files load in the right order and an error occurs because of a dependency. I'm fixing it right now, but maybe reloading the page will help with your issue.